One vertex per element, one color per generator, with an edge from x to x·s.
(9,10,13,16)(11,14,17,18)(12,15,20,22)(19,21,23,24)(25,26)(27,34)(28,36)(29,33)(30,31)(32,37)(35,39)(38,40)(1,2)(3,5)(4,6)(7,8)(9,10)(11,14)(12,15)(13,16)(17,18)(19,21)(20,22)(23,24)(25,27,31,33)(26,29,30,34)(28,35,37,40)(32,39,36,38)(1,2,4,6)(3,7,8,5)(11,17)(12,20)(14,18)(15,22)(26,30)(28,37)(29,34)(35,40)(3,8)(5,7)(9,10)(11,18)(12,15)(13,16)(14,17)(19,24)(20,22)(21,23)(25,28,31,37)(26,32,30,36)(27,35,33,40)(29,39,34,38)(1,3,4,8)(2,5,6,7)(9,11)(10,14)(12,19)(13,17)(15,21)(16,18)(20,23)(22,24)(25,29,31,34)(26,33,30,27)(28,38,37,39)(32,35,36,40)(1,2)(3,5)(4,6)(7,8)(9,12,13,20)(10,15,16,22)(11,19,17,23)(14,21,18,24)(25,30,31,26)(27,34,33,29)(28,36,37,32)(35,38,40,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.